Last week, we published our AMD 2nd Gen Ryzen Deep Dive, covering our testing and analysis of the latest generation of processors to come out from AMD. Highlights of the new products included better cache latencies, faster memory support, an increase in IPC, an overall performance gain over the first generation products, new power management methods for turbo frequencies, and very competitive pricing.

In our review, we had a change in some of the testing. The big differences in our testing for this review was two-fold: the jump from Windows 10 Pro RS2 to Windows 10 Pro RS3, and the inclusion of the Spectre and Meltdown patches to mitigate the potential security issues. These patches are still being rolled out by motherboard manufacturers, with the latest platforms being first in that queue. For our review, we tested the new processors with the latest OS updates and microcode updates, as well as re-testing the Intel Coffee Lake processors as well. Due to time restrictions, the older Ryzen 1000-series results were used.

Due to the tight deadline of our testing and results, we pushed both our CPU and gaming tests live without as much formal analysis as we typically like to do. All the parts were competitive, however it quickly became clear that some of our results were not aligned with those from other media. Initially we were under the impression that this was as a result of the Spectre and Meltdown (or Smeltdown) updates, as we were one of the few media outlets to go back and perform retesting under the new standard.

Nonetheless, we decided to take an extensive internal audit of our testing to ensure that our results were accurate and completely reproducible. Or, failing that, understanding why our results differed. No stone was left un-turned: hardware, software, firmware, tweaks, and code. As a result of that process we believe we have found the reason for our testing being so different from the results of others, and interestingly it opened a sizable can of worms we were not expecting.


An extract from our Power testing script

What our testing identified is that the source of the issue is actually down to timers. Windows uses timers for many things, such as synchronization or ensuring linearity, and there are sets of software relating to monitoring and overclocking that require the timer with the most granularity - specifically they often require the High Precision Event Timer (HPET). HPET is very important, especially when it comes to determining if 'one second' of PC time is the equivalent to 'one second' of real-world time - the way that Windows 8 and Windows 10 implements their timing strategy, compared to Windows 7, means that in rare circumstances the system time can be liable to clock shift over time. This is often highly dependent on how the motherboard manufacturer implements certain settings. HPET is a motherboard-level timer that, as the name implies, offers a very high level of timer precision beyond what other PC timers can provide, and can mitigate this issue. This timer has been shipping in PCs for over a decade, and under normal circumstances it should not be anything but a boon to Windows.

However, it sadly appears that reality diverges from theory – sometimes extensively so – and that our CPU benchmarks for the Ryzen 2000-series review were caught in the middle. Instead of being a benefit to testing, what our investigation found is that when HPET is forced as the sole system timer, it can  sometimes a hindrance to system performance, particularly gaming performance. Worse, because HPET is implemented differently on different platforms, the actual impact of enabling it isn't even consistent across vendors. Meaning that the effects of using HPET can vary from system to system, as well as the implementation.

And that brings us to the state HPET, our Ryzen 2000-series review, and CPU benchmarking in general. As we'll cover in the next few pages, HPET plays a very necessary and often very beneficial role in system timer accuracy; a role important enough that it's not desirable to completely disable HPET – and indeed in many systems this isn't even possible – all the while certain classes of software such as overclocking & monitoring software may even require it. However for a few different reasons it can also be a drain on system performance, and as a result HPET shouldn't always be used. So let's dive into the subject of hardware timers, precision, Smeltdown, and how it all came together to make a perfect storm of volatility for our Ryzen 2000-series review.

A Timely Re-Discovery
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  • samal90 - Sunday, April 29, 2018 - link

    I don't understand. The review should be made not based on how AMD or intel wants you to setup your PC, but how it ships by default. Most users don't fiddle with BIOS and don't understand HPET.
    The review should be done with default settings. You install the CPU, install windows and bam...review. Fiddling with options might be good as a side project to test stuff, but in most cases, people use it as is.
    Reply
  • patrickjp93 - Monday, April 30, 2018 - link

    Anandtech also caters to enthusiasts, so there's that to consider. Reply
  • tucode - Monday, April 30, 2018 - link

    yes, but default (out of box) settings are more useful and informative for basic hw comparison benchmarks

    then one can add extra 'tweaked' benchmark data same way as OC results
    also it would be nice to share/provide the what tweaks have been used (e.g. regedit file, etc)

    as for a lot of extra work arguments/comments, sure, but that's what makes the difference, and people who are interested (=enthusiasts) will happily look into it...and appreciate the extra effort
    Reply
  • whetstone - Wednesday, May 2, 2018 - link

    I have not read 23 pages of comments but …

    Concerning the RTC, you should take a look at GetSystemTimeAdjustment/SetSystemTimeAdjustment (windows) and hwclock (Linux).
    Reply
  • x0fff8 - Friday, May 4, 2018 - link

    Just curious, are the gaming benchmar results in the ryzen deep dive post updated yet today? Reply
  • MDD1963 - Monday, May 7, 2018 - link

    So were there more corrected/confirmed results coming, or , just this vague rehash of 'we blame chipset and WIndows timing'on our crappy results' fiasco for a summary :) Reply
  • jameswhatson - Wednesday, May 9, 2018 - link

    However, it sadly appears that reality diverges from theory – sometimes extensively so – and that our CPU benchmarks for the Ryzen 2000-series review were caught in the middle.

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  • Gamma9 - Saturday, May 12, 2018 - link

    Yeah thats what I thought it would be after watching AdoredTV's video on this. Reply
  • Gamma9 - Saturday, May 12, 2018 - link

    Ah no, no... I didn't think it was this I thought it would just be that the timers would be running slower on the AMD hardware. Reply
  • maverickmad - Tuesday, May 15, 2018 - link

    The HPET, despite its name, is not more accurate. The TSC timer is accurate to CPU clock-cycle precision, which is usually more than two orders of magnitude better than the HPET. shorturl.at/hzBFG Reply

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